This invention relates to an electromagnetic relay.
West German Utility Model Specification No. 7 144 972 discloses an electromagnetic relay having a coil wound on a bobbin, at least one movable contact and one fixed contact, and a casing including a base having bores in its bottom wall through which contact and coil terminals pass, and a cover having its lower edge engaging the upper side of the base. The space between the cover, the base and the relay body is filled with a sealant. To provide some means for positioning the relay body within the casing, simultaneously achieving a safe electrical insulation between the cover, which may consist of metal, and voltage carrying portions of the relay such as the contact terminals, an intermediate layer of insulating material or an insulating spacer must be provided between the cover and the relay body. Further and more exact fixing of the relay body within the casing, which would be desirable for structural and electrical reasons, might perhaps be achieved by accordingly dimensioning the intermediate layer or the spacer, e.g. by forming these portions with increased thickness. This, however, is apt to impede the sealant flow, thereby preventing a uniform and bubble-free embedding of the relay body at all sides thereof. After the relay body has been embedded in the sealant, an additional manufactural step is required to join the plane base plate with the unit thus obtained, which is a further drawback of the known relay.
U.S. Pat. No. 4,091,346 discloses a further relay, in which the base portion of the casing is provided with vertical walls. Since the terminals are embedded in the material of the base portion, it is not necessary to seal them by means of an additional casting material. There is a certain difficulty, however, to realize a hermetic seal between the base portion and the cover, particularly because the relay body is mounted in the base portion and adjusted there. The adjustment requires recesses to be provided in the casing wall which create additional sealing difficulties. Also, contact and coil spaces are not separated from each other in this known relay.
It is a basic object of the invention to provide a relay which can be manufactured economically with constant quality and in which the sealing can be effected by a small number of process steps.